Infineon Technologies IR3891MTR1PBF

Overview

IR3891MTR1PBF from Infineon Technologies (formerly International Rectifier) is a dual-output, 4A/phase synchronous buck regulator with integrated high- and low-side MOSFETs, drivers, and bootstrap diodes in a 5mm × 6mm PQFN package. It supports 1V–21V input, delivers 0.5V–0.86×PVin outputs, operates up to 1.5MHz, and features precision 0.5V ±1% reference voltage - used in server VRMs and telecom point-of-load systems.

For engineers reviewing the IR3891MTR1PBF datasheet, IR3891MTR1PBF pinout, IR3891MTR1PBF application, or IR3891MTR1PBF equivalent, key selection criteria include interleaved-phase current capability, programmable switching frequency (300–1500 kHz), thermal-compensated hiccup-mode overcurrent protection, sequencing support via Seq pin, and open-loop feedback line protection for robust power-up reliability.

Technical Context

The IR3891 implements a voltage-mode PWM controller with feed-forward line regulation and internal digital soft-start. Its dual-channel architecture uses interleaved switching to reduce input ripple current and capacitor stress, while independent error amplifiers with 20–40 MHz GBWP and 80–110 dB DC gain enable stable loop compensation across wide load and line variations.

Each channel integrates thermally compensated current sensing, overvoltage protection triggered at 115–125% V_REF, and precise power-good monitoring with 75–90% V_REF thresholds. The Rt/Sync pin supports either resistor-programmed free-running operation or external clock synchronization with 270–1650 kHz range and 100–200 ns pulse width tolerance.

Key Specifications

Pinout & Package

IR3891MTR1PBF is housed in a thermally enhanced 5mm × 6mm Power QFN (PQFN) package with exposed thermal pad, rated θ_JA = 24.7°C/W and θ_JB = 3.6°C/W. Pin numbering follows top-view orientation with dual-channel symmetry and dedicated power ground (PGnd) pins per phase.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output synchronous buck regulator applications.

Compared with MP8765GL-Z and TPS546D24RSAR, IR3891MTR1PBF offers analog-programmable frequency without digital overhead, superior thermal performance (θ_JB = 3.6°C/W), and integrated bootstrap diodes - making it optimal for cost-sensitive, thermally demanding analog-controlled PoL designs where PMBus adds unnecessary complexity.

Availability

IR3891MTR1PBF is available at Aetrix Electronics and suitable for server VRMs, telecom point-of-load systems, and embedded networking equipment requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for IR3891MTR1PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Infineon Technologies is a global semiconductor leader specializing in power management, sensor, and automotive ICs, with deep expertise in high-efficiency power conversion and ruggedized analog solutions.

The SupIRBuck® product line delivers highly integrated, easy-to-use DC/DC regulators targeting space-constrained, high-current point-of-load applications in computing, telecom, and storage infrastructure - emphasizing thermal robustness, protection completeness, and layout simplicity.

FAQ

What is the maximum supported input voltage for IR3891MTR1PBF?

The absolute maximum PVin rating is 25V, but recommended operating PVin is 1.0–21V per datasheet Section 4. Exceeding 21V risks violating SOA limits under transient conditions. For 24V bus applications, external clamping or pre-regulation is required to maintain reliability within specified thermal and electrical boundaries.

Does IR3891MTR1PBF require external bootstrap diodes?

No - the device integrates bootstrap diodes internally, eliminating the need for external components. Each BOOT pin connects directly to its respective SW pin through an on-die diode, reducing BOM count and PCB area. External 100nF ceramic capacitors between BOOT and SW remain mandatory for proper high-side gate drive operation.

How does the Seq pin function in dual-output sequencing?

The Seq pin connects exclusively to Channel 2's error amplifier and accepts an external voltage ramp (0–0.77V). When this voltage crosses the internal threshold (~250mV), Channel 2 enables after Channel 1, establishing controlled power-up order. Leaving Seq floating disables sequencing, allowing both channels to start simultaneously upon EN assertion.

What is the thermal performance difference between θJA and θJB ratings?

θ_JA = 24.7°C/W reflects junction-to-ambient resistance on a standardized test board; θ_JB = 3.6°C/W measures junction-to-PCB resistance, indicating superior heat transfer to the copper plane. This low θ_JB confirms effective thermal coupling to the PCB, enabling higher sustained power delivery when using adequate copper pour and thermal vias beneath the exposed pad.